With the advance of science and technology, the wireless communication products used in various fields, including industry, science and medicine, are gradually diversified. Among them, in-vehicle phones and mobile phones grow especially fast. The state-of-the-art communication devices feature portability and low power consumption. The high frequency and middle high-frequency performance of the resonators, filters, capacitors, etc. used in the mobile communication devices are considered to be very important. Further, how to reduce the size and power consumption of devices is also an important topic in designing products.
When used in a WLAN (Wireless Local Area Network) system operating at a frequency band of 5.25 GHz, the conventional microstrip antenna has too high a conductor ohmic loss because of the high operation frequency. In the same case, the conventional dielectric resonator antenna does not have any conductor ohmic loss but has high radiation efficiency, low consumption and a high gain. Therefore, the dielectric resonator antenna is very suitable to be used in such a high frequency band. The conventional dielectric resonator antenna usually uses a material having a permittivity of 20-30 and has a height higher than the microstrip antenna. Sometimes, a dielectric resonator antenna adopts a material having a high permittivity (normally higher than 70) to reduce the size thereof, and more particularly to reduce the height thereof. However, a high permittivity causes a decreased operation bandwidth, which usually cannot meet the requirement of the bandwidth.
The BaO-rare earth oxide-TiO2 system ceramic is one of the materials able to satisfy the abovementioned requirement. The BaO-rare earth oxide-TiO2 system ceramic not only is likely to realize the miniaturization of the antenna but also is likely to achieve a high permittivity and a low dielectric loss. However, the BaO-rare earth oxide-TiO2 system ceramic suitable for smaller high frequency devices has a very high permittivity. It is difficult and expensive to obtain a lower-permittivity BaO-rare earth oxide-TiO2 system ceramic via introducing other additional components.
Accordingly, the present invention proposes a novel and advanced dielectric resonator technology to overcome the abovementioned problems.